Rotatable welding gun

ABSTRACT

A rotatable welding gun with an axial expansion means for centering radially a mandrel inside a tube to be welded, a reel for wire of welding metal rigidly fixed to the torch and the mandrel, permitting the weld in front of the torch to be supplied with welding metal during the rotation of the rotatable members.

United States Patent 1191 1111 3,754,114 Peyrot Aug. 21, 1973 [541 ROTATABLE WELDING cum 2,117,931 1/1951 Bryant 219/125 R 1 3,268,706 8/1966 Lamin et al. 219/125 R X [761 lnvenm 391 Pun, avenue de 3,134,894 5/1964 Farnsu orth 219/125 R 39 General Lech", 3,125,670 3/1964 Hawthorne 219/120 R VflleJuIf, France 3,194,937 7/1965 'Brons =1 al 219/60 A [22] Filed: Jan. 28, 1972 Primary Examiner-J. V. Truhe Appl' 221A Assistant Examiner-L. A. Schutzman Attorney-Karl F. Flocks [30] Foreign Application Priority Data Apr. 14, 1971 France 7113182 I [57] ABSTRACT 219,125 agga 9 A rotatable welding gun with an axial expansion means [58] Fie'ld R 60 A for centering radially a mandrel inside a tube to be 57 R 61 5 welded, a reel for wire of welding metal rigidly fixed to the torch and the mandrel, permitting the weld in front of the torch to be supplied with welding metal during [56] g zi'fig gg the rotation of the rotatable members. 3,345,494 10/1967 Apblett, Jr. et al 219/60 A X 12 Claims, 5 Drawing Figures Paten ted Aug. 21, 1973 5 Sheets-Sheet 1 mm Ma Patented Aug. 21, 1973 3 Sheets-Sheet 2 Patented Aug. 21, 1973 3 Sheets-Sheet 5 Ill 1 ROTATABLE WELDING GUN The present invention relates to a rotatable welding gun, and more particularly to av gun for automatic welding with a tungsten electrode and with supply of welding metal under a. gaseous protecting flux.

Rotatable welding guns for carrying out automatically autogenous welding arealready known in the art, but it is sometimes advantageous to weld: a tube on to a head-plate with added weldingmetal. consequence, the present invention provides; a welding gum which. can be. used for welding tubes on thick platesirrespective of the geometry chosen by the welder, comprising deviceswhich make it possible: to control accurately the flow-ratesofi'the:circuits of gasandzwater and also the passage. of the: current, as a; function: of'the position of the electrodes during the execution of the weld; and bymeanszot? which: itis1alsopossibletosupply the electrode continuously withwireofa weldi'ngimetal-i while the. electrode, displaced; by the: rotatable gun,.f'ol lows its course: opposite the." circular weld? of a tube on: the base-plate.

The. protecting; gas.- may flow according-to the. prior art and in; known; manner, into the chamberfromswhich. it eupels the; oxidizing air and? thussupplies the:- con.- trolled. atmosphere: around? the weldingzone which: is; necessary for; satisfactory; execution oft-he weld:

However; it has: been found% that. although; when the: protecting: gas; is a gas having. as relatively; high: specific. weight such as; argon, thewelding-zone is suitably protected; on the; otherhandk when; an: extremely; lighta isv adopted; such:- asv helium: for: example; the: gas: has, a". tendency: to accumulate inthe: upper: portions and thei protection? ofi'the weld: leaves somethinggto be desired'i The inventiontherefore:alsoprovides:aJbeaI circum ferentialdiffusion @nozzle directediallroundlthe-circulan position; ofi'the' zoneto: be; welded, the device-comprim ing; at: leasta one axial? channel inside the: walls of the chamber; aa diffusing: ring of sintered metal}. a slotted; nozzle, the: lips of-"whichxl are: inclined radially: towards. the wall off the a head-plate to be welded; on -which tl'ie: gunis supported.

Other characteristic features and advantages-willi be" brought out in -thezdescription=which follows-below; reference. being; made to? the accompanying: drawings which show 'bytwayi of 'indication zbut notiin :a'ny: limita= tivesense, two formsofi'embodiment ofi theinvention;

ln:= the drawings:: FIG; la is a view in :elevation; .partly intcross-section; of I a. rotatable welding gun: accordinggto theinve'ntion; 1

FIG.- .Z -isa perspectiveviewoffan altemativeform' of construction;

FIG. 3 -isl a.view-- partly in'esectionwith" partswbroken away of the chamber: with.a:controlled atmosphere ac cording.: tothe: invention; which is: adapted'=to -the gun? intended 2 to weld; by. means of Jan electrode: 33won1a1 baserplate l3; The.welding ;head..60 of the-gun is: setin rotation when the operator; who holds-in hishand. the handle .10 securedion:the.:fiiied1:body;26rof thegun; .ac-'-- tuates the trigger 23;

The conduit 47 comprises the gas and water conduits and the electrical conductors which supply current to an eight track collector 61' on which eight corresponding brushes mounted on the rear block 62 which rotates with the head 60, supply the necessary power to the four conductors of the motor 25 with a tachometer dynamo, to the two wires of a motor 63 for driving the welding metal wire 64 wound on the reel 65, and to the twoconductors of a synchronizing signal transmitter.

It can be seen: that the welding metal 64 wound on the reel-'65 isdriven with an exact control of the length delivered by tworollers66= and 67, one being a supportingroller and the other a driving roller actuated by a drivi'ngfmotor acting. on the wire- 63" by means of a transmission. belt 68"' The wire 64-is guided in con'duits69 and 70 upstream and downstream: of the rollers 66 and- 67', and passes through" a central conduit (:not shown) which re-joins in: the head 60 a flexible wire guide 71", the orientation ofwhich can be adjusted as required in order topr'esent the: welding metal in agood: position" on: the weld to be recharged atvthe levelof the" base-plate 1-3 opposite" the electrode 33".

Itv can'beseen that the rotatable unitof the rear bloclt 62:" of the: head 60" and' the central sleeve inside which passes the wire: 64; rotates at will under the actionwhich is: applied: by the: operator who holds the handle 10;\-on? the contact trigger 23; The contact established by.- the: trigger 23- en'ergizes' the motor 25 which acts through: the intermediary of a reduction gear 72",. ona pinion=73 rigidlyfixed to'themoving'system, this pinion 13 engaginggwith thefixed toothedwheef7 t =onthe'cas mg;

According to:an alternative form shown inFlG. 2; a motor I'ZSdrivingthetoroh 31controls a shaft 75 parallel tothe axis x-y ot"the gun-'203.-A straight pinion 76, keyed: on: the: shaft-"75 engages with a reduction" gear wheelf'lfl ri'gidly fixed to a hollowsleeve or tube 78', on which: a system 79 is -freely mounted and I which: is rig idly-fixed to a: crank handle 80"which drives-two short shaftsrbl and' 82'i the welding 'metal wire 85 whicli returns along the axis x=-y andpasses into 1 the interior of the tube 7 8 The: wire 85 passes-out of the front" of the gun 203 through'ran' orifi ce 86'and' passes into a sheath 97 which offers it in the weldingsposition" inside a guide 88.

Thereflcan also' beseen amotor 89 for driving the ac tuating roll'ers'90=and'91" of thewinding reel83;

motor 89 rigidly fixed on the of the gun it 203;'-.operates a shaft 92on which is keyed a straight pinion 93 in'engagementwith "atoothed wheel '94'of-the system: 79: The wheel 9 4 is" coupled through a" unidirectional pawl: clutch locking devicewith a straight pinion 95 which rotates freely on the tube 7 8: straightpinion" 95; when it is engaged with the toothed wh'eel 94 c'an act tli'rough -th'e intermediary of a 'loosezpinion96g to rotate a pinion 97 ke ye'd on a shaft 98;. by meansofl which v a 90 bevel 1 gear 'r'eference 99"" permitswtheidrive of the pinion 9'1 actuating the rollers" of :thevwindinghreel 83"between which' thewire of weld ing-'metalflspasses;

In operation; the :driving motor 89of the rollers being- PP d; thefsta'rtinl-up of themotor *in "the 'direc-' tion of the-arrow f} fixedlydrivesthe toothed wh'eel -77 the crank-handle80'and the reel unit'83 for the wire in rotation about the axis x-y. The pinions 96 and 97 are freely driven in this turning movement without them having any movement of rotation about their axes 81 and 82 and no longitudinal displacement or any torsion force are applied on the wire 85.

The electrode 33 can thus be brought at will into a good working position, the telescopic mounting 104, and the pivot 102 providing a fine adjustment.

lf then the motor 89 is started-up which drives the toothed wheel 94 of the system 79 being able to rotate freely around the tube 78, the pinion 93 rotating in the direction of the arrow f1, the wheel 77 and the wheel 94 are both driven in the direction of the arrow f-,.

As soon as the speed of the wheel 94 becomes sufficient to cause the operation of the locking pawl device 100 which couples it to the pinion 95 in the system 79, the pinion 95 introduces a differential action in the direction of the arrow f, with respect to the crank handle 80.

The free pinion 96 in engagement with the pinion 95 and the pinion 97 then impart a driving movement to the wire 85 by means of the rollers 90 and 91, at the speed required so as to feed the weld opposite the electrode 33 of the torch.

When the gun is centered in operation by its mandrel ll inside the tube 12 and when the operator forces it axially into contact with the plate 13 on the abutment 14, the gas which fills the chamber 39 at a relatively low pressure with a flow-rate of 3 to 7 litres per second for example, is normally delivered between the leakage contact 105 towards the atmosphere along the headplate 13, especially if a gas as light as helium has been chosen to surround the weld.

in order to improve the protective effect on the zone 106 at all points, both before and during the passage of the electrode 33 and during the cooling after its passage, the invention provides around the torch 33 between the abutment 14 and the knurled abutment screw 34, a chamber 107 which channels the arrival of the gas in the immediate proximity of the welding zone 106 over a frusto-conical blowing layer inclined in the direction of the arrows f (see FIG. 3).

The chamber 107 comprises a transparent-wall 108 of quartz held between three metal claws 109 and in fluidtight contact with the axially adjacent parts through the intermediary of toric rings 115.

Each claw 109 is pierced with a channel 1 for leading-in the gas which supplies a collector 111 provided in the abutment ring 14, which is in turn in relation with the flattened slot of a nozzle 112 between the lips 113 and 114 of a peripheral lining which directs the layer of protective gas in the direction of the arrows j}, in the immediate contact of the zone 106.

The porous ring 116 of sintered metal, for example Poral, ensures a uniform diffusion over the whole periphery of the drusto-conical layer, despite the fact that the arrival of the gas is distributed only over three main sectors at the extremities of the three channels 110.

It will of course be understood that the present invention has been described above in the form of a preferred example given by way of indication and not in any limitative sense and that any equivalents may be introduced into its constituent elements without thereby departing from its scope as defined by the appended claims. I

I claim:

1. A rotatable welding gun comprising; a fixed body with a handle, a sheath for a fluid inlet and current supply leads extending inside said handle, a rotatable axial mandrel on one end of said fixed body, a torch disposed radially eccentric with respect to said mandrel, means for axially adjusting the position of said torch, adjustable expansion means for radially centering the mandrel inside a tube to be welded, a reel rigidly fixed to said mandrel from which wire welding metal may be unwound and fed up in front of said torch by roller means which carry said wire metal through a sleeve member up to said torch during rotation of rotatable parts which include a central tube rigidly fixed to said torch and to a driving unit for unwinding the wire, a driving motor for the torch on said fixed body and driving motor for the wire metal, said two motors having output pinions that are coupled together by means of an escapement mechanism comprising a unidirectional clutch of the free-wheel type and a transmission with a differential action.

2. A rotatable welding gun as claimed in claim 1 in which the rotatable parts comprise a welding head round a centering mandrel, a rear unit, the central sleeve joining rigidly together the said welding head and the rear unit, the said rear unit carrying a winding reel for wire of welding metal, a roller driving device for the said wire, a motor for setting in rotation the rotatable parts, the said motor driving a pinion which engages internally on a fixed toothed wheel rigidly fixed to the casing of the said gun.

3. A rotatable welding gun as claimed in claim 2, in which the said motor for setting the mobile system into rotation is a tacheometric dynamo motor coupled to a pulse emitter.

4. A rotatable welding gun as claimed in claim 3, in which the said welding wire driving device mounted on the said rear unit carries a driving motor for the wire, a transmission belt, a driving roller and a supporting roller.

5. A rotatable welding gun as claimed in claim 4, in which the casing carries a fixed-collector with eight tracks on which the corresponding brushes of the rear unit of the mobile system collect the power necessary for the four wires of the tacheometer motor, the two wires of the wire driving motor and the two wires of the pulse emitter.

6. A rotatable welding gun as claimed in claim 1, in which the said mechanism comprises a toothed wheel engaging with a first motor and freely mounted around the tube driven by a second motor, and a crank handle rigidly fixed to the said tube, a transmission with a differential driving action on the supply rollers of the wire being mounted eccentrically with respectto the tube on the said crank handle, the said mechanism of the free-wheel clutch device type permitting the introduction into the said transmission of a movement controlled by the said toothed wheel when the angular speed of the said wheel exceeds the angular speed of the said tube.

7. A rotatable welding gun as claimed in claim 6, in which the said crank handle carries three pinions in engagement with each other, the input pinion turning freely on the said tube and the output pinion being connected by the transmission to the welding wire feed rollers, the input pinion being driven in uni-directional rotation with respect to the crank handle by the pawlclutch device which couples it to the said toothed wheel driven by the first motor when the angular speed of the said wheel becomes greater than that of the tube driven by the second motor.

8. A rotatable welding gun as claimed in claim I, in which a controlled atmosphere chamber coupled to the body of the gun comprises a cylindrical wall and at least one longitudinal conduit in the interior of the said cylindrical wall coupling an inlet of protective gas coming from the sheath to a circular collector which diffuses the gas over a frusto-conical layer directly on the zone to be welded.

9. A welding gun as claimed in claim 8-, in which the said cylindrical wall is of quartz, two toric joints ensuring the fluid-tightness of the chamber at its extremities.

10. A welding gun as claimed in claim 9, in which the said quartz wall is gripped by three claws coupling the body of the gun to an abutment ring, the said ring comprising a collector coupled to the said longitudinal conduits. Y

11. A welding gun as claimed in claim 10, in which the said collector is coupled to a circular exhaust nozzle by means of a porous filter.

12. A gun as claimed in claim 11, in which the said nozzle is flattened to the form of a slot between two lips which incline the frusto-conical layer of gas towards the internal peripheral region of the said abutment ring, and towards the exterior with respect to the body of the gun so as to flow directly over the zone to be welded. l k k t l 

1. A rotatable welding gun comprising; a fixed body with a handle, a sheath for a fluid inlet and current supply leads extending inside said handle, a rotatable axial mandrel on one end of said fixed body, a torch disposed radially eccentric with respect to said mandrel, means for axially adjusting the position of said torch, adjustable expansion means for radially centering the mandrel inside a tube to be welded, a reel rigidly fixed to said mandrel from which wire welding metal may be unwound and fed up in front of said torch by roller means which carry said wire metal through a sleeve member up to said torch during rotation of rotatable parts which include a central tube rigidly fixed to said torch and to a driving unit for unwinding the wire, a driving motor for the torch on said fixed body and driving motor for the wire metal, said two motors having output pinions that are coupled together by means of an escaPement mechanism comprising a uni-directional clutch of the free-wheel type and a transmission with a differential action.
 2. A rotatable welding gun as claimed in claim 1 in which the rotatable parts comprise a welding head round a centering mandrel, a rear unit, the central sleeve joining rigidly together the said welding head and the rear unit, the said rear unit carrying a winding reel for wire of welding metal, a roller driving device for the said wire, a motor for setting in rotation the rotatable parts, the said motor driving a pinion which engages internally on a fixed toothed wheel rigidly fixed to the casing of the said gun.
 3. A rotatable welding gun as claimed in claim 2, in which the said motor for setting the mobile system into rotation is a tacheometric dynamo motor coupled to a pulse emitter.
 4. A rotatable welding gun as claimed in claim 3, in which the said welding wire driving device mounted on the said rear unit carries a driving motor for the wire, a transmission belt, a driving roller and a supporting roller.
 5. A rotatable welding gun as claimed in claim 4, in which the casing carries a fixed-collector with eight tracks on which the corresponding brushes of the rear unit of the mobile system collect the power necessary for the four wires of the tacheometer motor, the two wires of the wire driving motor and the two wires of the pulse emitter.
 6. A rotatable welding gun as claimed in claim 1, in which the said mechanism comprises a toothed wheel engaging with a first motor and freely mounted around the tube driven by a second motor, and a crank handle rigidly fixed to the said tube, a transmission with a differential driving action on the supply rollers of the wire being mounted eccentrically with respect to the tube on the said crank handle, the said mechanism of the free-wheel clutch device type permitting the introduction into the said transmission of a movement controlled by the said toothed wheel when the angular speed of the said wheel exceeds the angular speed of the said tube.
 7. A rotatable welding gun as claimed in claim 6, in which the said crank handle carries three pinions in engagement with each other, the input pinion turning freely on the said tube and the output pinion being connected by the transmission to the welding wire feed rollers, the input pinion being driven in uni-directional rotation with respect to the crank handle by the pawl-clutch device which couples it to the said toothed wheel driven by the first motor when the angular speed of the said wheel becomes greater than that of the tube driven by the second motor.
 8. A rotatable welding gun as claimed in claim 1, in which a controlled atmosphere chamber coupled to the body of the gun comprises a cylindrical wall and at least one longitudinal conduit in the interior of the said cylindrical wall coupling an inlet of protective gas coming from the sheath to a circular collector which diffuses the gas over a frusto-conical layer directly on the zone to be welded.
 9. A welding gun as claimed in claim 8, in which the said cylindrical wall is of quartz, two toric joints ensuring the fluid-tightness of the chamber at its extremities.
 10. A welding gun as claimed in claim 9, in which the said quartz wall is gripped by three claws coupling the body of the gun to an abutment ring, the said ring comprising a collector coupled to the said longitudinal conduits.
 11. A welding gun as claimed in claim 10, in which the said collector is coupled to a circular exhaust nozzle by means of a porous filter.
 12. A gun as claimed in claim 11, in which the said nozzle is flattened to the form of a slot between two lips which incline the frusto-conical layer of gas towards the internal peripheral region of the said abutment ring, and towards the exterior with respect to the body of the gun so as to flow directly over the zone to be welded. 